Internal frame optimized for stiffness and heat transfer

ABSTRACT

A thin portable electronic device with a display is described. The components of the electronic device can be arranged in stacked layers within an external housing where each of the stacked layers is located at a different height relative to the thickness of the device. One of the stacked layers can be internal metal frame. The internal metal frame can be configured to act as a heat spreader for heat generating components located in layers adjacent to the internal frame. Further, the internal metal frame can be configured to add to the overall structural stiffness of the device. In addition, the internal metal frame can be configured to provide attachment points for device components, such as the display, so that the device components can be coupled to the external housing via the internal metal frame.

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. Patent Application is a continuation of and claims priorityunder 35 U.S.C. §120 to co-pending U.S. application Ser. No. 12/859,702,filed Aug. 19, 2010 and entitled “INTERNAL FRAME OPTIMIZED FOR STIFFNESSAND HEAT TRANSFER” by Rothkopf et al. now U.S. Pat. No. 8,391,010 issuedMar. 5, 2013, which is incorporated by reference in its entirety for allpurposes.

BACKGROUND

1. Field of the Invention

The invention relates to consumer electronic devices and moreparticularly, methods and apparatus associated with the thermostructuraldesign of consumer electronic devices.

2. Description of the Related Art

From a visual stand point, users often find compact and sleek designs ofconsumer electronic devices more aesthetically appealing. As an example,portable electronic device designs that are both thin and light-weightare often popular with consumers. In some thin device designs, one faceof the device is almost entirely dedicated to a viewable portion of thedisplay while other input/output components are arranged around thesides and back of the device opposite the display. Typically, thedisplay is surrounded by a thin enclosure where the display driver, mainlogic board, battery and other interface circuitry are all packagedwithin the thin enclosure.

In the devices described in the previous paragraph, components such asthe processor and the display and other internal components generateheat. To preserve the longevity of electrical components in the deviceas well as for user comfort, it is desirable to prevent thermal hotspots from developing within the enclosure or on the surface of theenclosure. When a thin and compact enclosure is used, there is a minimumamount of space available for providing heat conduction paths within theenclosure or for adding thermal mass that acts as a heat sink. Also,when the over-all weight of the device is minimized andmanufacturability of the device is considered, it is undesirable toinclude parts whose sole purpose is only to address thermal issues.

In view of the above, enclosure components are desired that addressthermal issues while satisfying weight, structural and packagingconstraints associated with a light-weight portable electronic deviceemploying a thin and compact enclosure.

SUMMARY

Broadly speaking, the embodiments disclosed herein describe structuralcomponents well suited for use in consumer electronic devices, such aslaptops, cellphones, netbook computers, portable media players andtablet computers. In particular, structural components are describedthat address both strength and thermal issues associated with the designof a light-weight consumer electronic device with a thin and compactenclosure. Methods for forming these structural components are alsodescribed.

In one embodiment, the consumer electronic device can be a thin portableelectronic device with a display. The internal arrangement of thecomponents of the thin portable electronic device can be viewed as anumber of stacked layers. The stacked layers can be associated with aparticular height relative to the thickness of the device. Variousdevice components, such as but not limited to display circuitry, a CPU,speakers, memory, wireless communication circuitry and a battery can bearranged and distributed on the stacked layers.

One of the stacked layers can be an internal frame. The internal framecan be coupled to the external housing of the thin portable electronicdevice. The internal frame can be configured to provide heatdistribution capabilities, such as heat spreading, for components thatgenerate heat located in layers adjacent to the internal frame. Further,the internal frame can be used to add to the overall structuralstiffness of the device. In addition, the internal frame can be used asan attachment point for other device components used in the device, suchas the display.

In one embodiment, the internal frame can be an internal metal frameformed from a number of layers of different metals. For instance, theinternal metal frame can include a middle layer formed from a firstmetal situated between two outer layers formed from a second metal. Thefirst metal and the second metal can each be selected for their strengthand/or heat conduction properties. Further, the thickness of each of thelayers can be varied to enhance either its strength or thermalcharacteristics. In one embodiment, the different metal layers of theinternal metal frame can be joined using a cladding process.

In a particular embodiment, the first metal used in the middle layer canbe selected primarily for its heat conduction properties such that themiddle layer can act as a heat spreader while the second metal used inthe two outer layers can be primarily selected to improve the strengthof the internal metal frame and hence, the overall stiffness of thedevice. In general, the first metal and the second metal can selected toimprove one or more of heat conduction property, a strength property(e.g., stiffness), an environment property (e.g., corrosive resistance)and a cosmetic property (e.g., appearance of the device). As an example,the middle layer can be formed from copper, which is selected for itsthermal properties, and the two outer layers can be formed fromstainless steel, which is selected for its strength properties. Inanother embodiment, the second metal used in the two outer layers can beselected to allow each of the outer layers to act as heat spreaderswhile the first metal used in the middle layer can be selected for itsstrength properties.

When the first metal used in the middle layer of the internal metalframe is selected primarily selected for its thermal properties so thatthe middle layer can act as a heat spreader, one or more apertures canbe provided in the outer layers of the internal metal frame. Eachaperture can be located proximate to a heat generating component withinthe device. A thermal bridge can be provided that thermally links asurface associated with the heat generating component to the middlelayer of the internal metal frame via the aperture in the outer layerproximate to the heat generating component. In particular embodiments,the thermal bridge can be formed from a soldering material or athermally conductive adhesive tape.

Other aspects and advantages will become apparent from the followingdetailed description taken in conjunction with the accompanying drawingswhich illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The described embodiments will be readily understood by the followingdetailed description in conjunction with the accompanying drawings,wherein like reference numerals designate like structural elements, andin which:

FIG. 1A shows a top view of a portable electronic device in accordancewith the described embodiments.

FIG. 1B shows a bottom view of a portable electronic device inaccordance with the described embodiments.

FIG. 1C shows block diagram of a portable electronic device inaccordance with the described embodiments.

FIG. 1D shows a cross-sectional view of a portable electronic device inaccordance with the described embodiments.

FIGS. 2A and 2B show top and bottom views of an internal frame inaccordance with the described embodiments.

FIG. 2C shows a top view of an internal frame in accordance with thedescribed embodiments.

FIGS. 3A-3B shows a cross-sectional view of the internal frame inaccordance with the described embodiments.

FIGS. 4A-4B shows a cross-sectional view of the internal frame thermallylinked to a number of device components in accordance with the describedembodiments.

FIG. 5 is flow chart of a method of manufacturing a portable electronicdevice with an internal frame designed with specific thermostructuralproperties in accordance with the described embodiments.

FIG. 6 is a block diagram of a portable computing device configured as amedia player in accordance with the described embodiments.

DETAILED DESCRIPTION OF THE DESCRIBED EMBODIMENTS

In the following detailed description, numerous specific details are setforth to provide a thorough understanding of the concepts underlying thedescribed embodiments. It will be apparent, however, to one skilled inthe art that the described embodiments can be practiced without some orall of these specific details. In other instances, well known processsteps have not been described in detail in order to avoid unnecessarilyobscuring the underlying concepts.

A first factor that can be considered in the thermostructural design ofa thin and compact portable electronic device can be the placement ofthe components associated with the user interface. After determining anouter placement of the components, factors, such as internal packaging,weight, strength and stiffness needed to protect the device duringexpected operational conditions, can be considered in regards to thedesign of the housing. Then, thermal issues, such as preventing internalhot spots from developing can be considered. These design factors, whenconsidered together, can each affect one another. Thus, the design ofthe device can be an iterative process.

As an illustration of the thermostructural design process for a portabledevice, a device design is discussed in view of the factors described inthe preceding paragraphs. Typically, a portable device can include adisplay. The display and an input mechanism can usually be placed on oneface of the device. If desired, a thin-profile housing can be specifiedthat surrounds and encloses all but the portion of the display visibleto the user. The face opposite the display can be mostly structureassociated with housing but can include apertures for other inputdevices, such as a camera.

Along the edges of the housing, various input/output mechanisms can beplaced, such as volume switches, power buttons, data and powerconnectors, audio jacks and the like. The housing can include aperturesto accommodate the input/output mechanisms. The locations at which theinput/output mechanisms are placed can be selected to enhance theusability of the interface under conditions for which the device isintended to operate. For instance, for a device intended to be operatedwith a single hand, the input mechanisms, such as an audio controlswitch, can be placed at a location that are easily finger operatedwhile the device is held in the palm of the hand. Further, outputmechanisms, such as an audio jack, can be placed at locations that donot interfere with holding the device, such as on a top edge of thedevice.

Once the components of the user interface are placed, device componentsthat connect to and allow the portable electronic device to operate forits intended functions can be packaged within the enclosure. Examples ofinternal device components can include speakers, a microphone, a mainlogic board with a processor and memory, non-volatile storage, data andpower interface boards, a display driver and a battery. Some flexibilitycan be afforded in regards to the locations of the internal devicecomponents as long as sufficient space for needed connectors betweencomponents is available. Also, approaches, such as custom-shaped PCBs orbatteries, can be employed to allow available internal spaces to beefficiently utilized.

Once the user interface has been designed and the internal componentsare packaged in a suitably compact housing, thermal issues can beconsidered. Many internal components generate heat. To prevent the heatfrom building up in certain locations and possibly damaging the internalcomponents, mechanisms may be needed to dissipate and conduct heatinternally. The compact design of these devices can leave little roomfor convective cooling, i.e., allowing air to circulate in the device todissipate heat. Thus, other approaches may be needed to address internalcooling issues.

One approach to solving the cooling problem can be to provide one ormore structures configured to conduct heat away from and to differentinternal locations within the device. Besides being used for cooling,the structures can also be used to enhance to the structural propertiesof the device, such as adding to the over-all stiffness of the device.In particular embodiments, internal frames designed to satisfy thermaland structural constraints associated with the design and operation of aportable electronic device are described. The internal frames can beconfigured to conduct and dissipate heat generated within the enclosure.Further, the internal frames can be configured to add to the over-allstrength of the device.

The thermostructural design of these internal frames and their use inportable electronic devices are discussed below with reference to FIGS.1A-5. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these figures is forexplanatory purposes only and should not be construed as limiting. Inparticular, with respect to FIGS. 1A-1D, an overall configuration of aportable electronic device is described. The device can include aninternal frame with heat conduction capabilities configured to satisfythermal and structural constraints associated with the design andoperation of the device, which is discussed. In FIGS. 2A-2C, variousembodiments of the internal frame are shown and discussed. With respectto FIGS. 3A and 3B, internal structures and materials associated withthe internal frames are described. A coupling of the internal frame tovarious device components and associated manufacturing methods arediscussed in relation to FIGS. 4A, 4B and 5. Finally, portable computingdevice configured as a media player is described with respect to FIG. 6.

FIGS. 1A and 1B show a top and side view of a portable electronic device10 in accordance with the described embodiments. The device 10 caninclude a housing 100 that surrounds a display 104. The housing 100 canbe designed with a relatively thin-profile. The housing 100 provides anopening 108 in which the display 104 is placed. A cover glass 106 isplaced over the display 104. The cover glass 106 helps to seal theopening 108. The device 10 can include a touch screen associated withthe display (not shown).

A significant fraction of the area of the top face of the device 10 isoccupied by the display 104. This fraction can be smaller or larger ifdesired. Also, the fraction dedicated to the display can vary fromdevice to device. In some embodiments, the device 10 may not eveninclude a display.

As previously described above, the display 104 can be a component in auser interface associated with the device 10. Other device componentsthat contribute to the user interface or the over-all operation of thedevice 10 are distributed at various locations on the housing 100 of thedevice 10. The placement of these components can affect the internalpackaging and hence the location of heat generating components withinthe device.

As an example of an outer arrangement of the device components, an inputbutton 114 is located on the front face. In one embodiment, the inputbutton 114 can be used to receive an input indicating a desire to returnthe device to a particular state, such as a “home” state. A volumeswitch 112 that can be used to adjust a volume associated with variousaudio applications implemented on the device can be located on one sideof the housing 100. A power switch 110 is located on the top side ofdevice 10 and an audio jack and an opening for a data/power connector islocated on a bottom side of the housing 100 opposite the top side. Thebottom side of the housing 100 includes an aperture. A lens 115 for acamera can be placed in the aperture.

FIG. 1C shows a block diagram of the device 10. A display 104, a battery132, a touchscreen 122, a wireless communication interface 126, adisplay controller 120, audio components 124 (e.g., speakers), can eachbe coupled to a main logic board (MLB) 105. The device 10 can includeother components (not shown), such as a Sim card, a microphone and anon-volatile memory and is not limited to the components shown in FIG.1C. The MLB 105 can include a processor and a memory. The processor andmemory can execute various programming instructions to allow the deviceperform various functions. The user interface, described above, can beconsidered to allow a user to select and adjust the various functionsthat are available on the device 10. In particular embodiments, thesefunctions can be provided as user selectable application programs thatare stored on the device.

FIG. 1D shows a cross-sectional view of a portable electronic device 10in accordance with the described embodiments. An enclosure can be formedfrom the top glass 106 and the housing 100. Other enclosureconfiguration are possible and the described embodiments are not limitedto this example. As is illustrated in FIG. 1D, the housing 100 canprovide a cavity that is covered by the top glass 106. The housing 100can include an outer surface and an inner surface where the innercontour profile 117 of the inner surface can be different from the outercontour profile of the housing 100.

Within an enclosure, such as an enclosure including the top glass 106and the housing 100, various internal device components, such as devicecomponents associated with the user interface that allow the device 10to operate for its intended functions, are packaged. For the purposes ofdiscussion, the internal device components can be considered to bearranged in a number of stacked layers. The height of each of thestacked layers can be specified relative to the overall thickness 136 ofthe device. For instance, a height of the middle of the top glass 106can be specified as a first fraction of the overall thickness 136 whilea height of the battery 132 can be specified as a second fraction of theoverall thickness 136.

The display screen of the display 104 can be located directly below thetop glass 106. In one embodiment, the display screen and its associateddisplay driver circuitry can be packaged together as part of the display104. Below display 104, device circuitry 130, such as a main logic boardor circuitry associated with other components, and a battery 132, whichprovides power to the device 10, can be located.

As previously described and as shown in the FIG. 1D, the internalcomponents can be tightly packed leaving little room for pathways thatallow cooling via air circulation to be effective for the internalcomponents that generate heat. Another approach to addressing internalheating issues that can be used in conjunction with or in lieu ofconvective air cooling is to place a thermally conductive materialproximate to the heating source. The thermally conductive material canabsorb and conduct heat away from an internal heat source, such as aheat generating internal device component, to lower a temperature nearthe heat source during operation of the device.

In one embodiment, the thermally conductive material can be incorporatedinto an internal structure associated with the device 10, such asinternal frame 140. The internal frame 140, which is described in moredetail with respect to the following figures, can be configured toconduct heat away from one or more device components and to add to theoverall strength of the device. For instance, the internal frame 140 canbe configured to add to the overall stiffness of the device 10, such asan ability to resist bending moments experienced by the housing 100.

In the FIG. 1D, the internal frame 140 is located in at a height belowthe display 104 and above the device circuitry 130. The internal frame140 can be placed in this location to draw away heat generated by thedisplay circuitry. Further, one or more heat sources associated with thedevice circuitry 130 can be positioned proximate the internal frame 140to allow heat from these components to be conducted into the internalframe 140 and away from the heat source.

Other packaging configurations are possible. Thus, in other embodiments,the internal frame 140 can be located at different heights relative tothe overall thickness 136 of the device and can also be locatedproximate to different device components. Further, a device, such as 10,can include multiple frames, such as 140 and described embodiments arenot limited to a use of a single internal frame 140.

In one embodiment, the internal frame 140 can be used as an attachmentpoint for other device components. For example, the internal frame 140can be attached to mounting surface, such as 134 a and 134 b, on thehousing 100 via fasteners or using a bonding agent. Then, other devicecomponents, such as the display 104 can be coupled to the internal frame140 rather than directly to the housing 100. One advantage of couplingthe display 104 to the housing via the internal frame 140 is that thedisplay can be somewhat isolated from bending moments associated withthe housing 100, i.e., bending moments generated on the housing can bedissipated into the internal frame 140. Isolating the display 104 frombending moments associated with the housing 100 can prevent damage tothe display 104, such as cracking, from occurring.

FIGS. 2A and 2B show top 142 a and bottom 142 b views of an internalframe 140 in accordance with the described embodiments. In oneembodiment, the internal frame can be formed as a multi-layered sheet,such as a sheet including a number of metal layers (see FIGS. 3A and 3Bfor a cross-section of the internal frame 140 including its differentlayers). In a particular embodiment, the internal frame 140 can beformed having a middle layer of a first material sandwiched between twoouter layers of a second material. The materials used in the middlelayer and the outer layer can be selected for their thermal properties,such as thermal conductivity, and/or strength properties.

In one embodiment, the first material used in the middle layer can beselected primarily for its thermal properties while the second materialused in the outer layers can be selected primarily for its strengthproperties. As an example, a middle layer of copper can be sandwichedbetween two layers of a stainless steel, such as Iconel.™ The thermalconductivity of the copper is about 25 times greater than the Iconel,™whereas the stainless steel is much more resistant to bending than thecopper, which can be quite pliable. In one embodiment, the middle layercan make up about 50% of the thickness of the internal frame and theouter layers can each make up about 25% if the thickness of the internalframe. When the middle layer is copper and the outer layers arestainless steel, this configuration retains about 94% of the stiffnessof an internal frame of the same thickness made from just stainlesssteel.

Other combinations of material are possible and the embodiments describeherein are not limited to a combination of copper and stainless steel.For instance, other metal combinations, such as a aluminum and stainlesssteel, can also be employed. Further, non-metal and metal materials ordifferent types of non-metal materials can be combined to form aninternal frame, such as 140.

In a particular embodiment, an internal frame, such as 140, having acopper layer sandwiched between to two stainless steel layers, can beformed using a cladding process. In one implementation of a claddingprocess, a sheet of copper can be compressed at a high pressure betweentwo sheets of stainless steel to join the sheets. As an example, thesheets can be squeezed with a high pressure between two rollers as partof the cladding process. The sheets formed via the cladding process canbe cut to form the internal frame 140 shown in the figures.

In metallurgy, cladding is the bonding together of dissimilar metals. Itis distinct from welding or gluing as a method to fasten the metalstogether. Cladding can be often achieved by extruding two metals througha die as well as pressing or rolling sheets together under highpressure. The cladding process “metallurgically” bonds metals together,producing a continuous strip that can be annealed, rolled, and slit tomeet very precise electrical, thermal, and/or mechanical end-use needs.Clad inlays or overlays on one or both base metal surfaces with preciousor non-precious metal combinations can be provided.

In general, cladding can refer to a deposition process where one metalis coated with another metal or a substrate material, which can benon-metallic, is coated with another metal. In some cladding processes,the metal can be melted on to the substrate, such as via a lasercladding process. Thus, the embodiments described herein are not limitedto a cladding process where metal sheets are joined together underhigh-pressures, such as via rollers.

For an internal frame, such as 140, where the middle conductive layer issandwiched between two outer layers with a significantly lower thermalconductivity, the outer layers can include one or more apertures thatexpose the middle conductive layer. The apertures can be provided toallow a better thermal link to be formed between the middle conductivelayers and a heat generating component. In particular embodiments, asurface of the heat generating component can be thermally linked to themiddle conductive layer via soldering material or via thermallyconductive tape. Double-sided thermally conductive tapes are often usedto join heat sinks to components, such as processors, in computerapplications. In the embodiments described herein, the double-sidedthermally conductive tape or a soldering material can be used to bondand hence thermally link a surface of a heat generating component to theinternal frame 140.

On the internal frame 140, the position of the apertures can be selectedto be close to heat generating components within the portable device. Anumber of apertures, 150 a-f, are shown on the top 142 a and bottom 142b of the internal frame 140. As is shown, the aperture locations canvary from the top 142 a to the bottom 142 b of the internal frame 140.As is shown in FIGS. 2A and 2B, the aperture locations on the top 142 aare at different locations than on the bottom 142 b. Further, there aremore apertures on the top 142 a than on the bottom 142 b of the internalframe 140.

In general, the locations of apertures in outer layer of an internalframe 140 can vary from device to device depending on the heatgenerating components used with each device and the internal packagingschema selected for each device. In one embodiment, the apertures can belocated on only one side of the internal frame, such as only the topside or the bottom side. In another embodiments, the outer layers can bethermally conductive and the middle layer can be provided for strength,such as stainless steel sandwiched between two copper layers. In thisexample, apertures in the outer layer are not necessary for thermallinking purposes because a surface of a heat generating source can bedirectly bonded to the thermally conductive outer layers.

FIG. 2C shows a top view of an internal frame 160 in accordance with thedescribed embodiments. In one embodiment, the internal frame 160 caninclude one or more apertures, such as 162, that go entirely through theinternal frame 160. The one or more apertures can be used to place acomponent, such as a connector through the internal frame 160. Inaddition, apertures that go entirely through the frame 160 can beprovided to fasten the internal frame 160 to another component, such asa device housing 100 described with respect to FIGS. 1A, 1B and 1D.

As described above with respect to FIGS. 2A and 2B, the internal frame160 can include one or more apertures in its outer layers that expose asolid middle layer. In one embodiment, the apertures can be filled-inwith a material the same as or different from the material used in themiddle layer. Aperture 150 a is an example of a filled-in aperture. Inanother embodiment, the apertures may not be filled in and thus, aslight recess or cavity is possible where an aperture is provided toexpose the middle conductive layer. Aperture 164 is an example of anaperture in the outer layer of the internal frame 160 that forms acavity.

In one embodiment, a raised thermal connector, such as 166, can beprovided. The raised thermal connector 166 can be formed from athermally conductive material such as a copper. The raised thermalconnector 166 can be used to thermally link a heat source located atsome height above the internal frame 160 to a conductive layer of theinternal frame, such as the middle layer. A raised thermal connector canbe used when a heat generating component is located at a distance abovethe connector that is too large to use direct soldering to provide thethermal link. In one embodiment, the raised thermal connector 166 can bethermally insulated via an outer insulation layer, such as 168.

In a particular embodiment, the raised thermal connector 166 can becoupled to the internal frame 160 after it is formed. For example, theraised thermal connector 166 can be soldered or taped onto the internalframe 160. In one embodiment, when apertures are provided in the outerlayers to expose a thermally conductive middle layer, a raised thermalconnector 166 can be provided at one of these locations to thermallylink, via the connector, a surface of a heat generating device componentto the middle layer of the device frame. An example of a raised thermalconnector positioned in this matter is also described with respect toFIG. 4B.

FIGS. 3A-3B shows a cross-sectional view of an internal frame, such as across-section that can be used in internal frame, such as 150 or 160(Internal frame 150 and 160 are described with respect to FIGS. 2A-2C.).In FIG. 3A, a cross-section including three layers is shown. The threelayers include outer layers 170 a and 170 b and a middle layer 172disposed between these two outer layers.

The thicknesses of each of the middle and outer layers can vary. In oneembodiment, the thicknesses of each of the outer layers can beapproximately the same. In another embodiment, the thicknesses of eachof the outer layers can be different. The thickness of the middle layercan be the same or different than the thicknesses of each of the twoouter layers. In a particular embodiment, the thicknesses of each of thetwo outer layers can be proximately the same where a combined thicknessof the two outer layers is proximately equal to the thickness of themiddle layer.

The thicknesses of each layer can be varied to adjust the strength,weight, and/or thermal properties of the internal frame. For instance, astainless steel layer can be made thicker to increase an overallstrength of the internal frame. In another example, a copper layer canbe made thicker to increase the thermal mass of the internal frame.

A first aperture 171 a can be provided in the top outer layer 170 a anda second aperture 171 b can be provided in the bottom outer layer 170 b.The aperture 171 a in the top outer layer 170 a is shown as not filledin so that a small cavity is formed proximate to the aperture. Theaperture 171 b in outer layer 170 b is shown as filled with the samematerial as the middle layer. A few methods for filling in an aperture,such as 171 b, are described in the following paragraph.

In one embodiment, the aperture 171 b can be totally or partially filledin during the cladding process. For instance, the outer and middlelayers can be sufficiently squeezed together such that a portion of themiddle layer protrudes through the aperture. In another embodiment, theapertures can be filled in after the cladding process. The apertures canbe filled with a material that is the same or different than thematerial of the middle layer. For example, the cavity formed from theaperture can be filled with a soldering material that is provided tothermally link the middle layer 172 to a surface of a heat generatingcomponent. As another example, the internal frame can be dipped intoanother material to fill in one or more of the apertures.

FIG. 3B shows another embodiment of a cross section that can be utilizedwith an internal frame. In this embodiment, a middle layer 172 issandwiched between two outer layers 170 a and 170 b. However, a portionof the middle layer 172 is somewhat thermally isolated from anotherportion of the middle layer. The thermal isolation is illustrated by thematerial 173 that extends from the top layer 170 a to the 170 b.

In some embodiments, it may be desirable to reduce the heat transferrate between one portion of the internal frame and another portion ofthe internal frame. This can be accomplished by placing a material witha lower conductivity between two portions of the thermally conductivemiddle layer. For instance, the middle layer 172 can be formed from twoor more separate strips of material that are sandwiched between sheetsincluding the outer layers. During the cladding process, in the gapbetween the strips, the outer layers can be squeezed together to jointhe top and bottom layers and provide a reduced heat transfer ratebetween the portions of the middle layer 172. A similar process, asdescribed in the previous paragraph, can be employed to thermally linktwo layers. For instance, in FIG. 3B, if the top layers are a thermallyconductive material, such as copper, and the middle layer is a lessconductive material such as stainless steel formed from separate strips,then, during the cladding process, the top and bottom copper layers canbe squeezed together through the gaps in the stainless steel strips tothermally link the top and bottom copper layers.

FIGS. 4A-4B shows a cross-sectional view of an internal frame thermallylinked to a number of device components in accordance with the describedembodiments. A typical direction of heat transfer into the middle layeris indicated by the arrows. In FIG. 4A, different device components areshown linked to a cross section of the internal frame shown in FIG. 3A.In this example, the middle layer 172 of the internal frame can beformed from a thermally conductive material, such as copper, while theouter layers can be formed from a material that is stronger than thecopper, such as stainless steel. Apertures can be provided in the outerlayers to expose the middle layer to allow for a better thermal link tobe formed between the middle layer and surfaces of heat generatingcomponents proximate to each aperture.

In FIG. 4A, controller circuitry 186 can be located above top layer 170a. For instance, the controller circuitry 186 can be display circuitryas was described with respect to FIG. 1D. A PCB 180 can be located belowthe internal frame. The PCB 180 can include a number of components, suchas 182 a and 182 b. In one embodiment, the PCB can be a main logic boardthat includes a processor and a memory.

The aperture 171 a in outer layer 170 a can be located below a highheating area 188 associated with the controller circuitry 186. Theaperture 171 a is not filled in. A thermal bridge 184 b, such as asoldering material, can be used to provide a thermal link between asurface of the device circuitry 186 and the middle layer 172. The use ofthermal bridge, such as 184 b, can be desirable because an air gapbetween the high heating area and the thermal bridge can act as aninsulator that prevents heat from being conducted into the middle layer.Leaving a cavity in which the thermal bridge can be placed can allow thecontroller circuitry to be placed closer to the internal frame sinceadditional space between the internal frame and the surface of thecontroller circuitry is not needed for the thermal bridge. Duringoperation, heat generated in the high heating area 188 can be conductedinto the middle layer 172 and away from the high heating area 188. Thus,the temperature proximate to the high heating area can be reduced viathe internal frame.

The aperture 171 b in the outer layer 170 b is filled in. A thermalbridge 184 a is provided between a surface of the PCB component 182 aand the middle layer 172. The thermal bridge 184 a can increase a spacebetween the PCB component 182 a and the internal frame since theaperture 171 b is filled in and does not provide a cavity in which thethermal bridge can sit. In one embodiment, the thermal 184 a bridge canbe a thermally conductive adhesive, such as a double-sided adhesivetape.

When thermal bridge 184 a is used near an aperture, such as 171 b, thethermal bridge 184 a can be larger or smaller than the area of theaperture. In the example in FIG. 4A, the thermal bridge is shown asbeing bigger than the aperture 171 b. The area of the thermal bridge,such as 184 a, can be selected to ensure that a proper bond ismaintained during operation of the device.

As is shown in FIG. 4A, only certain components of a PCB, such as thecomponents that generate the most heat, may be thermally linked to theinternal frame whereas less hot components may not be thermally linkedto the internal frame. To illustrate this point, PCB component 182 a isshown thermally linked to the internal frame while PCB component 182 bis not shown thermally linked to the internal frame. Depending on adesign of a particular board and the number of its associatedcomponents, one or more components associated with the board can bethermally linked to the internal frame.

In FIG. 4B, a cross sectional view of device components thermally linkedto an internal frame is shown. In the cross section illustrated in FIG.4B, a top layer 170 a of the internal frame includes two apertures thatexpose a thermally conductive middle layer 172. The bottom layer 170 bdoes not include any apertures in this cross section. On the top layer170 a, one of the apertures proximate to thermal bridge 194 is filled-inwhile another of the apertures proximate to thermal bridge 196 is notfilled in. A PCB 190 including a PCB component 192 is located above theinternal frame. Another device component 195 that is not associated withthe PCB 190 is shown located above the PCB 190.

The PCB board is orientated so that a heat generating surface of the PCBcomponent faces the internal frame. When a thermally conductive internalframe is employed, the orientation/location of other internalcomponents, such as a PCB, can be adjusted so that surfaces associatedwith heat generating components can be thermally linked to the internalframe. Further, the desire to facilitate thermal linkage between adevice component on a PCB and the internal frame can also be a factor inthe design of the PCB, i.e., the device component can be arranged on thePCB such that a thermal linkage is easily facilitated.

In FIG. 4B, a surface of the PCB component 192, which is a heatgenerating component, is shown thermally linked to the middle layer 172of the internal frame via thermal bridge 194. In addition, a surface ofthe component 195, which is also a heat generating component, is shownlinked to middle layer 172 of the internal frame via thermal connector198. The thermal connector 198 is coupled to the middle layer 172 and asurface of the device component 195 via thermal bridges 196. Aspreviously described with respect to FIG. 2C, the thermal connector 198can include an outer thermally insulating layer surrounding a thermallyconductive core. In this example, the thermal connector 198 is shownextending above the level of the PCB 190 to reach the heating generatingcomponent 195.

FIG. 5 is a flow chart of a method 200 of manufacturing a portableelectronic device with an internal frame designed with specificthermostructural properties in accordance with the describedembodiments. In 202, an internal frame including a number of materiallayers can be configured. The configuration process can involveselecting a number of layers, a thickness of each layer and the strengthand thermal properties desired for each layer. The strength and thermalproperties desired for each layer can affect a material selected foreach layer.

In the embodiment, where a layer selected for its thermal properties issandwiched between two outer layers selected to add strength to theinternal frame, one or more apertures can be configured in the outerlayers. These apertures can be provided to allow a better thermal linkto be formed between the middle layer of the internal frame and a heatgenerating surface of an internal device component. In 202, a placementof these apertures can be determined.

In 204, the internal frame with the selected aperture locations, thermaland strength properties can be generated. In one embodiment, theinternal frame can be formed using a cladding process. In 206, duringthe assembly process for the electronic device, surfaces associated withheat generating components within the electronic device can be thermallylinked to the internal frame. In 208, the internal frame can bemechanically linked to the housing of the electronic device. In 210, oneor more device components can be mechanically linked to the internalframe.

In some embodiments, a device component, such as a display, can be bothmechanically and thermally linked to the internal frame. In otherembodiments, a device component can be mechanically linked but notthermally linked to the internal frame. In yet other embodiments, adevice component can be thermally linked to the internal frame andmechanically secured to the housing via other structural components.

In particular embodiments, the portable computing device can beassembled using a computer aided manufacturing and assembly process. Thecomputer aided manufacturing and assembly process can involve the use ofmultiple devices, such as multiple devices configured in an assemblyline configuration. For instance, a computer aided machine can beconfigured to form the apertures at different location by removingmaterial after the cladding process or by forming apertures in thesheets prior to the cladding process. As another example, a roboticdevice can be configured to thermal link a heat generating component tothe internal frame, such as via a soldering process.

FIG. 6 is a block diagram of a media player 300 in accordance with thedescribed embodiments. The media player 300 includes a processor 302that pertains to a microprocessor or controller for controlling theoverall operation of the media player 300. The media player 300 storesmedia data pertaining to media items in a file system 304 and a cache306. The file system 304 is, typically, a storage disk or a plurality ofdisks. The file system typically provides high capacity storagecapability for the media player 300. However, since the access time tothe file system 304 is relatively slow, the media player 300 alsoincludes a cache 306. The cache 306 is, for example, Random-AccessMemory (RAM) provided by semiconductor memory. The relative access timeto the cache 306 is substantially shorter than for the file system 304.However, the cache 306 does not have the large storage capacity of thefile system 304.

Further, the file system 304, when active, consumes more power than doesthe cache 306. The power consumption is particularly important when themedia player 300 is a portable media player that is powered by a battery(not shown).

The media player 300 also includes a user input device 308 that allows auser of the media player 300 to interact with the media player 300. Forexample, the user input device 308 can take a variety of forms, such asa button, keypad, dial, etc. Still further, the media player 300includes a display 310 (screen display) that can be controlled by theprocessor 302 to display information to the user. A data bus 311 canfacilitate data transfer between at least the file system 304, the cache306, the processor 302, and the CODEC 312.

In one embodiment, the media player 300 serves to store a plurality ofmedia items (e.g., songs) in the file system 304. When a user desires tohave the media player play a particular media item, a list of availablemedia items is displayed on the display 310. Then, using the user inputdevice 308, a user can select one of the available media items. Theprocessor 302, upon receiving a selection of a particular media item,supplies the media data (e.g., audio file) for the particular media itemto a coder/decoder (CODEC) 312. The CODEC 312 then produces analogoutput signals for a speaker 314. The speaker 314 can be a speakerinternal to the media player 400 or external to the media player 300.For example, headphones or earphones that connect to the media player300 would be considered an external speaker.

The various aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination.Various aspects of the described embodiments can be implemented bysoftware, hardware or a combination of hardware and software. Thedescribed embodiments can also be embodied as computer readable code ona computer readable medium for controlling manufacturing operations oras computer readable code on a computer readable medium for controllinga manufacturing line. The computer readable medium is any data storagedevice that can store data which can thereafter be read by a computersystem. Examples of the computer readable medium include read-onlymemory, random-access memory, CD-ROMs, DVDs, magnetic tape, and opticaldata storage devices. The computer readable medium can also bedistributed over network-coupled computer systems so that the computerreadable code is stored and executed in a distributed fashion.

The many features and advantages of the present invention are apparentfrom the written description and, thus, it is intended by the appendedclaims to cover all such features and advantages of the invention.Further, since numerous modifications and changes will readily occur tothose skilled in the art, the invention should not be limited to theexact construction and operation as illustrated and described. Hence,all suitable modifications and equivalents may be resorted to as fallingwithin the scope of the invention.

What is claimed is:
 1. A structural frame component for an electronicdevice, comprising: a first layer formed from a first material, thefirst material configured to add structural stiffness to the electronicdevice; a second layer and a third layer disposed on opposing surfacesof the first layer, wherein the second and third layers are formed frommaterials having a thermal conductivity greater than the first layer; anopening fully extending through the first layer; and a bridge structuredisposed within the opening and thermally coupled to the second andthird layers, wherein the bridge structure allows heat to transferbetween the second layer and the third layer.
 2. The structural framecomponent as recited in claim 1, wherein the first layer is formed froma first metal and the second and third layers are formed from a secondmetal.
 3. The structural frame component as recited in claim 2, whereinthe first metal is steel and the second metal is copper.
 4. Thestructural frame component as recited in claim 2, wherein the first,second and third layers are joined via a cladding process.
 5. Thestructural frame component as recited in claim 4, wherein the bridgestructure is formed by extruding portions of the second and third layersinto the opening in the first layer during the cladding process.
 6. Thestructural frame component as recited in claim 1, wherein the bridgestructure comprises a layer of thermally conductive solder.
 7. Thestructural frame component as recited in claim 1, wherein the bridgestructure comprises a layer of thermally conductive tape.
 8. Thestructural frame component as recited in claim 1, wherein the bridgestructure is aligned with a heat generating component thermally coupledto the first layer.
 9. A portable electronic device, comprising: ahousing forming an external surface for the electronic device andincluding an opening; a display disposed within the opening in thehousing; an internal frame coupled to one or more interior surfaces ofthe housing, the internal frame further comprising: a middle layerformed from a first material and having an opening extending through themiddle layer, the first material configured to add structural stiffnessto the electronic device, and a first outer layer and a second outerlayer, the first and second outer layers disposed on opposing surfacesof the middle layer, wherein the first and second outer layers areformed from materials configured to conduct heat; and an electroniccomponent disposed within the housing and thermally coupled to theinternal frame, wherein the first and second outer layers spread andtransfer heat generated by the component to the housing.
 10. Theportable electronic device as recited in claim 9, wherein the first andsecond outer layers are formed from materials having a thermalconductivity greater than the first material used to form the middlelayer.
 11. The portable electronic device as recited in claim 10,wherein the first and second outer layers are formed from a materialhaving a thermal conductivity at least 10 times greater than the thermalconductivity of the first material.
 12. The portable electronic deviceas recited in claim 10, further comprising: a thermally conductivefiller disposed within the opening and thermally coupled to the firstand second outer layers, wherein the thermally conductive filler allowsheat to transfer between the first outer layer and the second outerlayer.
 13. The portable electronic device as recited in claim 12,wherein the thermally conductive filler is a layer of thermallyconductive tape.
 14. The portable electronic device as recited in claim12, wherein the thermally conductive filler is made from thermallyconductive solder.
 15. The portable electronic device as recited inclaim 12, wherein the electronic component is coupled to the internalframe proximate to the thermally conductive filler, the thermallyconductive filler allowing the heat generated by the electroniccomponent to transfer between the first and second outer layers.
 16. Theportable electronic device as recited in claim 15, wherein theelectronic component is thermally coupled to the internal frame by athermally conductive adhesive.
 17. The portable electronic device asrecited in claim 15, further comprising a raised thermal connectorcoupled to the internal frame and the electronic component, wherein thethermal connector transfers heat from the electronic component to theinternal frame.
 18. The portable electronic device as recited in claim15, wherein a combined thickness of the first and second outer layers isapproximately equal to a thickness of the middle layer.
 19. The portableelectronic device as recited in claim 18, wherein the middle layer issteel and the first and second outer layers are copper.
 20. The portableelectronic device as recited in claim 19, wherein the middle layer andfirst and second outer layers are joined using a cladding process.